This invention relates to the field of agricultural engineering, and particularly to an improvement in apparatus for distributing anhydrous ammonia as a fertilizer to the soil.
Such apparatus normally includes a wheeled supply tank, a wheeled implement having applicators to deposit the ammonia in the soil, means whereby the implement is drawn behind a vehicle such as a tractor and the tank is drawn behind the implement, a flow meter to regulate the flow of ammonia to the applicators, piping and hose connecting the tank to the meter and the meter to the apparatus, and means actuable by the tractor operator for controlling the flow of ammonia from the tank to the flow meter.
One arrangement known for this purpose is shown in U.S. Pat. No. 3,905,323 to Ahlers, et al., which teaches the use of an arrangement mounted on the implement and including a rotary valve and a linear fluid motor connected to actuate the valve, under the control of the tractor operator, from the hydraulic console of the tractor. This arrangement has numerous advantages pointed out by the patentee, but also suffers from some disadvantages.
In the first place, the conversion of the linear motion of the fluid motor into rotary motion of the valve, while mechanically conventional, occupies an unnecessarily large space and has moving parts of considerable dimensions located in the open for easy interference by trash from the field of other adventitious objects. In the second place, the structure of the patent is all permanently mounted on the implement, so that if a farmer has more than one application implement, he must also have the same plurality of fluid motors, control valves, and regulators, even though a single ammonia tank can be used with any of the implements. Yet another defect is that the piston of a linear fluid motor is exposed to the dust and other abrasives of the environment and so is subject to severe wear.